Cyclic derivatives of arylboronic acids and of 1,2- and 1,3-diols and process for preparing same



CYCLIC DERIVATIVES F ARYLBORONIC ACIDS AND OF 1,2- AND 1,3-DIOLS AND PROCESS FOR PREPARING SAME Jean-Marie Farthouat, Romainville, France, assiguor, by rnesne assignments, to Roussel-UCLAF, S.A., Paris, France, a corporation of France No Drawing. Filed Dec. 14, 1960, Ser. No. 75,678 7 Claims. (Cl. 2 60340.9)

The present invention relates to the preparation of cyclic derivatives of arylboronic acids whose structure is represented by the general formula v 0-0 Ar-B (C )n wherein Ar -is an aryl radical which may be substituted or unsubstituted, n is equal to 0 or 1, and wherein the free valences of the carbon atoms carry either hydrogen or organic radicals.

Derivatives (1) result from the condensation of arylboronic acids with 1,2- and 1,3-diols, and preferably with diols of said type possessing physiologic properties, since the properties are magnified by the arylboronic acids, so that the corresponding derivatives (I) constiute therapeutic substances of great interest.

In the copending application No. 821,653, now Patent 3,038,926 the applicant has described compounds within the scope of general formula (I) together with a process for their preparation, said proces comprising condensing the arylboronic acid with the 1,2- or 1,3-diol by heating the reactants in anhydrous medium, the pH value being that of the reaction medium. The process is based on the apparent structure of the derivatives (I) and on the procedure used for their formation, both facts leading quite naturally to consider these compounds cyclic diesters of arylboronic acids and of diols, to which the conventional conditions of esterificatiou apply.

A thorough study of the chemical properties and of the structure of the derivatives (I), however, has shown that the latter should rather be considered as heterocyclic boron derivatives, that is, dioxaborolanes (n:0) or dioxaborinanes (nzl).

This fact results, on the one hand, from the very great stability of these compounds towards hydrolysis. Indeed, it is well known that boronic esters, generally, are on the contrary very readily hydrolyzable products, and that mere exposure to atmospheric humidity is often sufficient to effect the separation into boric acid and alcohol.

It has been found, on the other hand, that when a 1,2 or a 1,3-diol is added to an aqueous alkaline solution of an arylboronic acid, the diol dissolves progressively even :if originally water-insoluble.

3,222,379 Patented Dec. 7, 1965 "ice present invention. Said process comprises condensing an arylboronic acid having the formula /OH Ar-B wherein Ar has the hereinbefore given meaning, in the presence of an alkaline solution, and subsequently acidifying the reaction medium in order to precipitate out the desired compound.

The alkaline solution may be a solution of a strong organic or mineral base in Water, in an organic solvent, or in a mixture of both.

Various embodiments of the process may be used within the above mentioned scope.

In an embodiment of the process, an alkaline solution of arylboronic acid is prepared by dissolving it in excess aqueous solution of sodium or potassium hydroxide; the diol is added preferably in stoichionietric ratio, and starring is carried out to complete dissolution. The resultant compound is then precipitated with an acid; it is sucked almost dry, dried, and purified by recrystallization from an appropriate solvent.

In other embodiments according to the process, both constituents are mixed together before treatment with an alkaline solution; the procedure is carried out at room temperature, or above, as the case may be; the diol, or the acid, or both are dissolved in an appropriate solvent prior to being carried in alkaline medium. The reaction is carried out in the presence of sodium or potassium hydroxide, or in the presence of any other mineral or organic base insuring a sufficiently alkaline pH to the reaction medium so that the reactants will dissolve. The alkaline solutions employed may be purely aqueous, aqueous-alcoholic, or alcoholic, or obtained with any other appropriate solvents or mixture thereof.

The following examples are given merely for illustrative purposes, and the scope of the present invention is not to be limited thereto. The melting points given are the instantaneous melting points determined on a Maquenne block.

The compounds prepared according to the examples, and this is true generally of the derivatives (I), offer, with respect to the constituents from which they have been obtained, properties which are often very advantageous. Thus, the solubilities of the condensation products are, generally, much weaker than the solubilities of the original materials; also, their pharmacodynarnic properties are more powerful or more subtle, and they have less toxicity.

EXAMPLE I Z-p-tolyl-5-methyl-5-n-pr0pyl-1 ,3,2-di0xab0rinane 13 g. of p-tolylboronic acid are dissolved in a solution containing 10 g. of caustic soda and 100 ml. of water. 13.2 g. of Z-methyl-Z-n-propyl-l,3-propanediol are dissolved in 200 ml. of water. The two solutions are then mixed and, after a few moments the resultant solution is acidified with hydrochloric acid to pH 6. The product precipitates out in crystalline form; it is then sucked almost dry, dried, and recrystallized from ethanol. Melting point 54 C. Yield EXAMPLE II 2-p-t0lyl-4-o-t0loxymethyl-I ,3,2-di0xab0r0lane 7.47 g. of p-tolylboronic acid are dissolved in 750 ml.

.of aqueous N-potassium hydroxide solution: 10 g. of

cresoxypropane-diol are then added, with vigorous stirring. When dissolution is complete, the mixture is acidified with hydrochloric acid to pH 7. The product preless crystals.

cipitates out as an oil which soon sets to a mass. This is sucked almost dry, dried, and recrystallized from hexane. Colourless crystals. Melting point 42 C. Yield 70%.

EXAMPLE III 2,1-cis-ptolyl-4-paranifrophenyl-5dichloroacetamido- 1,3,2-dixab0rinane 177-178 C. Yield 80%.

EXAMPLE IV 2pcarboxyphenyl-S-methyl-5-n-propyl-1,3,2-di0xaborinane A solution containing 20 g. of 2-methyl-2-n-propyl- 1.3-propanediol and 300 ml. of water is added to a solution made of 16.6 g. of p-carb-oxyphenylboronic acid in 150 ml. of 2 N sodium hydroxide. The resultant solution is stirred for a few moments; it is then acidified with hydrochloric acid to pH 2. The product precipitates out in the form of colourless crystals. These are sucked almost dry, dried, and recrystallized from methanol. Melting point 2l8220 C. Yield 80%.

EXAMPLE V Z-p carboxyphenyl-4-p-chl0r0phenyl-4,5,5,-trimethyl- 1,3,2-dioxabor0la'ne A solution containing 2.6 g. of 2-p-chlorophenyl-3- methyl-2,3-butanediol in 50 ml. of methanol is slowly added with vigorous stirring, to a solution made of 2 g.

'of p-carboxy-phenylboronic acid in 20 ml. of 2 N potassium hydroxide. When the addition is complete, stirring is continued until a perfectly clear solution is obtained. The resultant solution is then acidified with hydrochloric acid to pH 2. The product precipitates out as an oil which is taken up in a boiling hexane-cyclohexane mixture. The product crystallizes out on cooling. Colour- Melting point l75178 C. Yield 50%.

EXAMPLE VI 2pcarb0xyphenyl-4-o-toloxymethyl-1,3,2-di0xaborolane A solution containing 10.9 g. of l-o-cresoxy-propane- 2,3-diol and 40 ml. of methanol is added to a solution made of g. of p-carboxyphenylboronic acid in 50 ml. of 2.5 N sodium hydroxide. After stirring for a few moments, the methanol is distilled off under reduced pressure. The resultant solution is acidified with hydrochloric acid to pH 2. The product precipitates out in the form of colourless crystals. These are sucked almost dry, dried and recrystallized from methanol. Colourless crystals. Melting point 2102ll C. Yield 80%.

EXAMPLE VII 160a,] 7a-p-tolyllborondioxy9a-flu0r0-116,21dihydroxy- I,4-pregnadiene-3,ZO-dione 9.85 mg. of 9ot-flu'oro-116,1604,l7a-21-tetrahydroxy-L4- pregnadiene-3,20-dione (triamcinolone) are added with vigorous stirring to a solution containing 3.61 mg. of p-tolylboronic acid and 2 ml. of N/ 10 sodium hydroxide, and dissolve little by little. The resultant solutionis then filtered, and acidified with hydrochloric acid. The product precipitates out in the form of colourless crystals which are recrystallized from an alcohol-water mixture.

Melting point 200-210 C. Yield 50%.

4 EXAMPLE VIII p-Tolylborondioxy-glucochloralose 2.34 g. of chloralose are added, with vigorous stirring, to a solution containing 1 g. of p-tolylboronic acid in 16 ml. of N-sodium hydroxide, and dissolved little by little. The resultant solution is acidified with hydrochloric acid to pH 1. The product precipitates out in the form of colourless crystals. Melting point C.

It is to be understood that the present invention is not to be restricted to the embodiments described which have been given merely for illustrative purposes.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. Process for the preparation of organic boron derivatives selected from the group consisting of the arylborolanes having the general formula:

R1 O( JRz .Ar-B

0-oR3 1'1. and the aryloborinaneshaving the general formula:

in which formulae Ar is a radical selected from the group consisting of the phenyl, tolyl and carboxyphenyl groups, R R R and R are each a radical selected from the group consisting of hydrogen, lower alkyl, tolyloxy lower alkyl, phenyl and monochloro-substituted phenyl groups and, when taken together and with the OC groups to which they are attached, form the residue of a compound selected from the group consisting of the l6,l7-dihydroxy steroids of the pregnadiene series and the vicinal diols of the glucose series, and R R R and R are each selected from the group consisting of hydrogen, lower alkyl, phenyl, mononitro-substituted phenyl and OL-SllbStltlltBd acetamido groups, said process comprising condensing, in an alkaline reaction medium, an arylboronic acild having the formula:

with a diol selected from the group consisting of 1,2-diols having the general formula:

and 1,3-diols having the general formula:

Ar, R R R 1K R R R and R havng the aforementioned meanings, and subsequently acidifying the react on medium, thereby precipitating said organic boron derivative and recovering said derivative.

2. Process for the preparation of organic boron derivatives selected from the group consisting of the arylborolanes having the general formula:

and the arylborinanes having the general formula:

O-GH: R:

in which formulae Ar is a radical selected from the group consisting of the phenyl, tolyl and carboxyphenyl groups, R R R and R are each a radical selected from the group consisting of hydrogen, lower alkyl, tolyloxy lower alkyl, phenyl and monochloro-substituted phenyl groups and, when taken together and with the OC groups to which they are attached, form the residue of a compound selected from the group consisting of the 16,17-dihydroxy steriods of the pregnadiene series and the vicinal diols of the glucose series, and R R R and R are each selected from the group consisting of hydrogen, lower alkyl, phenyl, mononitro-substitutcd phenyl and a-substituted aceta-rnido groups, said process comprising adding a diol selected from the group consisting of 1,2-diols having the general formula:

and 1,3-dio1s having the general formula:

to an alkaline solution of an arylboronic acid having the formula Ar, R R R R R R R and R having the aforementioned meanings, and subsequently acidifying the reaction medium to precipitate out said organic boron dcrivative and recovering said derivative.

3. Process for the preparation of organic boron derivatives selected from the group consisting of the arylborolanes having the general formula:

and the arylborinanes having the general formula:

O-GH, R5

in which formulae Ar is a radical selected from the group consisting of the phenyl, tolyl and carboxyphenyl groups, R R R and R are each a radical selected from the group consisting of hydrogen, lower .alkyl, tolyloxy lower alkyl, phenyl and monochloro-substituted phenyl groups and, when taken together and with the OC groups to which they are attached, form the residue of a compound selected from the group consisting of the 16,17-dihydroxy steroids of the pregnadiene series and the vicinal diols of the glucose series, and R R R7 and R are each selected from the group consisting of hydrogen, lower alkyl, phenyl, mononitro-substituted phenyl and a-substituted acetamido groups, said process comprising mixing an aqueous solution of a diol selected from the group consisting of 1,2-diols having the general formula;

Ri\ /Ra HO'jO-C-OH R; R0 and 1,3-diols having the general formula:

R5 R6 R1 OHOH CC-OH a with an alkaline solution of an arylboronic acid having the formula OH ArB Ar, R R R R R R R and R having the afore mentioned meanings, and subsequently acidifying the reaction medium to precipitate out said organic boron derivative and recovering sa-id derivative.

4. Process as claimed in claim 3, wherein said aqueous solution of the diol further contains as co-solvent an alcohol.

5. Process for the preparation of organic boron derivatives selected from the group consisting of the arylborolanes having the general formula:

R1 O-(E-R:

Ar-B

o-o-n, i. and the arylborinanes having the general formula:

O-CH: R5

in which formulate Ar is a radical selected from the group consisting of the phenyl, tolyl and carboxyphenyl groups, R R R and R are each a radical selected from the group consisting of hydrogen, lower alkyl, tolyloxy lower alkyl, phenyl .and monochloro-substituted phenyl groups and, when taken together and with the OC groups to which they are attached, form the residue of a compound selected from the group consisting of the 16,17-dihydroxy steroids of the pregnadiene series and the vicinal diols of the glucose series, and R R R and R are each selected from the group consisting of hydrogen, lower alkyl, phenyl, mononitro-substituted phenyl and (Z-SllbStituted acetamido groups, said process comprising condensing at room temperature in an alkaline aqueous medium an arylboronic acid having the formula ArB with a diol selected from the group consisting of 1,2-diols having the general formula:

action medium, thereby precipitating said organic boron derivative and recovering said derivative.

6. Process as claimed in claim 1, wherein the-alkalinity OTHER REFERENCES of said reaction medium is obtained by means of a strong Kuivna et a]; Org Chem; VOL 19 Pages 780 3 base selected from the group consisting of organlc and (1954) mineral bases- Sugihara et 211.: J. Am. Chem. Soc., vol. 80, pages 7. Process as claimed in claim 1 wherein said alkaline 5 2443 2446 (1958). reaction medium is an aqueous medlum' The Merck Index, sixth ed., pages 223-224.

- T i 1. 31 References Cited by the Exammer (lggisell Technical ranslatlons v0 1 page 2 UNITED STATES PATENTS 2 31 003 4 1953 Thomas 26() 462 1O LEWIS G0TTS,Prlmary Examm'er- 3,005,839 10/1961 Leeson et a1. 260-397.45 DUVAL T. MCCUTCHEN, Examiner. 

1. PROCESS FOR THE PREPARATION OF ORGANIC BORON DERIVATIVES SELECTED FROM THE GROUP CONSISTING OF THE ARYLBOROLANES HAVING THE GENERAL FORMULA: 